Unveiling the Burden of Hepatitis A in Salerno, Italy: A Comprehensive 9-Year Retrospective Study (2015-2023) on the Seroprevalence of HAV Antibodies and Age/Sex Distribution.

Hepatitis A virus (HAV) infection is a significant global cause of viral hepatitis. At present, the anti-HAV vaccine in Italy is proposed exclusively for specific high-risk groups, and a universal vaccination program is not implemented. This study aimed to assess the level of immunity against HAV in patients of both sexes across age groups ranging from 0 to 95 years admitted to the San Giovanni di Dio e Ruggi d'Aragona Hospital in Salerno, Italy, over a 9-year period (2015-2023). The total HAV seroprevalence by chemiluminescence Vitros system immunodiagnostics (ortho-diagnostics) was obtained by database analysis, stratifying patients for gender and age group in both the pre-pandemic (2015-2019) and pandemic (2020-2023) periods. Out of 28,104 samples collected in 2015-2023, 20,613 resulted positive by total HAV immune screening, with a significant reduction in the annualized proportion of events during the pandemic period compared to the pre-pandemic period. HAV was more abundant in males than females in both periods (exceeding the 70%), with a statistically significant decrease in HAV in females in 2015-2019. The 61-70-year-old age group is more susceptible for both genders, with a strong deviation from the 41-50-year-old age group compared to the 51-60-year-old group. The pandemic period affected the number of analyzed samples in 2020. The study revealed high HAV seroprevalence, especially in males and individuals aged 61-70 years. There was a notable decrease in seroprevalence during the pandemic compared to pre-pandemic years. These results emphasize the need for ongoing monitoring and suggest that a universal vaccination program could address regional immunity gaps and lower disease incidence.